Introduction

The OWASP CSRFGuard library is integrated through the use of a JavaEE Filter and exposes various automated and manual ways to integrate per-session or pseudo-per-request tokens into HTML.

Description

Overview

OWASP CSRFGuard implements a variant of the synchronizer token pattern to mitigate the risk of CSRF attacks. In order to implement this pattern, CSRFGuard must offer the capability to place the CSRF prevention token within the HTML produced by the protected web application. CSRFGuard 3 provides developers more fine grain control over the injection of the token. Developers can inject the token in their HTML using either dynamic JavaScript DOM manipulation or a JSP tag library. CSRFGuard no longer intercepts and modifies the HttpServletResponse object as was done in previous releases. The currently available token injection strategies are designed to make the integration of CSRFGuard more feasible and scalable within current enterprise web applications. Developers are encouraged to make use of both the JavaScript DOM Manipulation and the JSP tag library strategies for a complete token injection strategy. The JavaScript DOM Manipulation strategy is ideal as it is automated and requires minimal effort on behalf of the developer. In the event the JavaScript solution is insufficient within a particular application context, developers should leverage the JSP tag library. The purpose of this article is to describe the token injection strategies offered by OWASP CSRFGuard 3.

JavaScript DOM Manipulation

OWASP CSRFGuard 3 supports the ability to dynamically inject CSRF prevention tokens throughout the DOM currently loaded in the user's browser. This strategy is extremely valuable with regards to server-side performance as it simply requires the serving of a dynamic JavaScript file. There is little to no performance hit when the fetched dynamic JavaScript updates the browser's DOM. Making use of the JavaScript token injection solution requires the developer map a Servlet and place a JavaScript HTML tag within all pages sending requests to protected application resources. Developers are strongly encouraged to leverage the JavaScript token injection strategy by default. This strategy requires minimal effort on behalf of the developer as most of the token injection logic is automated. In the event that the JavaScript automated solution may be insufficient for a specific application context, developers should leverage the OWASP CSRFGuard JSP tag library.

Note: Use of JavaScript DOM Manipulation is required for Ajax support.

CSRFGuard Architecture

What is CSRFGuard?

OWASP CSRFGuard provides:

A library that implements a variant of the synchronizer token pattern to mitigate the risk of Cross-Site Request Forgery (CSRF) attacks.

A JavaEE Filter and exposes various automated and manual ways to integrate per-session or pseudo-per-request tokens into HTML.